This invention relates to new and useful improvements in trip mechanisms for ground engaging implements mounted upon a shank or the like and which are adapted to trip and return if the implement on the end of the shank, strikes an obstruction such as a rock, root or the like.
The majority of implement trip release mechanisms include a coil spring which compresses as the obstruction is engaged. However, as the degree of tripping increases, the coil spring pressure increases but the leverage of the assembly usually decreases. The movement of the trip mechanism and hence the pressure generated thereby, is restricted inasmuch as the pivotal connection between the spring and the shank assembly cannot pass through an over center position otherwise the shank would lock in an "up" position.
Because it cannot be over centered, the trip height of the shank assembly is limited so that damage can occur particularly when a relatively immovable obstruction is reached such as a rock which may be close to or even extend slightly above the surface of the ground.
Furthermore, another problem experienced by conventional shank tripping assemblies is the shock of the returning mechanism bottoming out on a solid mounting bracket thus causing stress and fatique. This occurs when the obstruction is finally passed and the heavy duty coil spring, which is usually fully compressed at this point, snaps the ground engaging implement back into position with considerable force.
Applicant is aware of the following patents in this general field: namely U.S. Pat. Nos. 3,662,839, 3,527,307, 2,395,342, 3,981,367, 3,098,529, 2,850,956 and 3,108,643. However, none of these overcome disadvantages inherent with such tripping devices.